Germ cells and the seminiferous epithelium cycle in the wild rodent Oxymycterus rufus (Rodentia: Cricetidae)

Oxymycterus rufus is a wild rodent that inhabits one of the world hotspots known as the Atlantic Rain Forest in Brazil. Due to the lack of reproductive data regarding such species, the present study aimed to describe O. rufus spermatogenic process through morphometrical and stereological analyses. To do so, testicular fragments of five sexually mature males were routinely processed for light and transmission electron microscopy. The results showed that each seminiferous epithelium cycle corresponded to 6.58 days, while the entire spermatogenic process lasted 29.61 days. The coefficient of spermatogonial mitoses was 5.64 and 2.79 spermatids were produced from each primary spermatocyte in pachytene. The spermatogenesis yield was 11.98 cells. The Sertoli cell index was 4.29, while its overall support capacity was 8.21 cells. The testicular sperm reserve was 183.5 x 10 6 cells, while 962.00 x 10 6 spermatids were found per gram of testis. The daily sperm production per testis and per gram of testis was 28.56 x 10 6 and 73.13 x 10 6 sperm, respectively. Therefore, the short duration of the seminiferous epithelium cycle along with rapid production of sperm indicates that O. rufus shows high efficiency in spermatogenesis.